Levich Institute Seminar Announcement, 01/30/2007

Tuesday, 01/30/2007
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Professor Michael Booty
Mathematical Sciences Department
New Jersey Institute of Technology
(Currently on Sabbatical at CCNY)

"Steady and Tip-Streaming Solutions of a Slender Surfactant-Coated Bubble in an Extensional Flow"

ABSTRACT



Slender body theory is used to find the steady deformation and time-dependent evolution of an axisymmetric inviscid bubble in a zero-Reynolds-number extensional flow when insoluble surfactant is present on the bubble surface.

The solutions show steady ellipsoidal bubbles that are completely covered by surfactant and, at increasing strain rate, solutions that are surfactant-free on a central cylindrical part with semi-ellipsoidal surfactant-covered end caps. Simple expressions are found for the steady-state response relation between the capillary number and the bubble slenderness ratio, which show the presence of a finite critical capillary number (and hence a finite critical imposed strain rate) above which the steady solutions cease to exist. Simplified equations are shown that describe time-dependent behavior reminiscent of tip-streaming when the capillary number is above critical.

Recent results are described indicating how effects such as interior bubble viscosity or solubility of surfactant in the exterior bulk flow can modify the solution structure.

BRIEF ACADEMIC/EMPLOYMENT BACKGROUND:


Michael Booty received graduate and undergraduate degrees from the University of London and University of Cambridge before taking postdoctoral positions at the University of Utrecht and Northwestern University. He then joined the faculty at Southern Methodist University before taking up his current position at New Jersey Institute of Technology. Apart from fluid mechanics, he has studied problems in heat transfer and combustion modeling, electromagnetic theory, and microwave heating. He is currently on leave and visiting at City College.